A brief description will be made below of idle mode of a Mobile Station (MS) and a paging group in relation to exemplary embodiments of the present invention.
Generally, idle mode is intended as a mechanism to allow an MS to become periodically available for downlink broadcast traffic messaging without requiring the MS to register to any particular Base Station (BS) as the MS moves in a radio link environment populated by multiple BSs.
If the MS has not received traffic from a BS for a predetermined time, it may transition to the idle mode to save power. In the idle mode, the MS receives a broadcast message (e.g. a paging message) from the BS during an available interval and determines whether to transition to normal mode or to stay in the idle mode. Also, the MS may notify a paging controller of its location by location update in the idle mode.
The idle mode may be beneficial to the MS by relieving the MS of an active requirement for handover and normal operational requirements. The idle mode restricts the MS's activity to scanning during discrete periods, so that the MS conserves power and operation resources.
Besides, the idle mode may benefit a network and a BS by providing a simple and timely scheme for alerting an MS to pending downlink traffic directed toward the MS and by eliminating an air interface and network handover traffic from an inactive MS.
Paging is a function of, upon generation of an incoming call in mobile communications, locating an MS for which the incoming call is intended (e.g. detecting a BS or a Mobile Switching Center (MSC) to which the MS belongs). A plurality of BSs supporting the idle mode may be divided into specified paging groups, covering paging areas.
The paging groups are logical groups. The purpose of these paging groups is to offer a contiguous coverage area in which the MS can be paged on a downlink if there is traffic targeted at it. Preferably, the paging groups are large enough for an MS to stay most of its time within the same paging group and small enough to render paging overhead reasonable.
A paging group may include one or more BSs and one BS may be a member of one or more paging groups. The paging groups are defined in a management system. A paging group may use a paging group-action backbone message. The paging controller uses another backbone message, paging-announce, to manage the list of MSs in the idle mode and initiate paging of an MS on all BSs belonging to a paging group.